Transpositional modulation communications

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium for receiving, by a first device, a first signal from a second device, the first signal including a carrier signal modulated with a first modulation signal. Detecting a frequency of the carrier signal by performing a carrier extraction (CAREX) process on the first signal. Adding a second modulation signal to the carrier signal of the first signal to produce a combined signal, wherein the second modulation signal is a transpositional modulation (TM) signal and the first modulation signal is a non-TM signal. Transmitting the combined signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/139,214, filed on Apr. 26, 2016, now U.S. Pat.No. 9,628,318, which is hereby incorporated by reference in itsentirety.

BACKGROUND

Carrier modulation techniques are used to transmit information signalsfrom one location to another. Traditional signal modulation techniquesinclude, for example, amplitude modulation (AM), frequency modulation(FM), and phase modulation (PM). In addition, complex modulationtechniques exist that incorporate aspects of AM, FM, and PM such asquadrature phase shift keying (QPSK), amplitude phase shift keying(APSK) and including quadrature amplitude modulation (QAM).

SUMMARY

This specification relates to methods and systems for combiningtranspositional modulation (TM) signals with traditional modulation(non-TM) signals. More specifically, the specification relates tomethods and systems for receiving an existing non-TM signal and adding aTM signal to the carrier of the non-TM signal with minimal or nointerference to the non-TM signal. In addition, the specificationrelates to methods and systems for communications between devices usinga combined traditional modulation and TM signal on the same carriersignal. Although discussed in the context of TM, implementations of thepresent disclosure also may be applicable to other signal types.

In general, innovative aspects of the subject matter described in thisspecification can be embodied in methods that include the actions ofreceiving, by a first device, a first signal from a second device, thefirst signal including a carrier signal modulated with a firstmodulation signal. Detecting a frequency of the carrier signal byperforming a carrier extraction (CAREX) process on the first signal.Adding a second modulation signal to the carrier signal of the firstsignal to produce a combined signal, where the second modulation signalis a transpositional modulation (TM) signal and the first modulationsignal is a non-TM signal. Transmitting the combined signal. Otherimplementations of this aspect include corresponding systems, apparatus,and computer programs, configured to perform the actions of the methods,encoded on computer storage devices. These and other implementations caneach optionally include one or more of the following features.

Some implementations include synchronizing a phase of the combinedsignal with a phase of the first signal.

In some implementations, adding the second modulation signal to thecarrier signal includes modulating a third harmonic signal of thecarrier signal of the first signal with data to produce the secondmodulation signal, and combining the second modulation signal with thefirst signal.

In some implementations, adding the second modulation signal to thecarrier signal includes generating a second harmonic signal of thecarrier signal and a third harmonic signal of the carrier signal.Modulating the third harmonic signal with a data signal. Mixing themodulated third harmonic signal with the second harmonic signal toproduce the second modulation signal. And, combining the secondmodulation signal with the first signal. Some implementations includesynchronizing a phase of the second modulation signal with a phase ofthe first signal.

In some implementations, the first modulation signal is one of phasemodulation, frequency modulation, binary phase shift keying, quadraturephase-shift keying, amplitude modulation, or quadrature amplitudemodulation.

In some implementations, detecting a frequency of the carrier signalincludes detecting a center frequency of the first signal. Detecting afrequency of a third signal. Determining a difference signal between thecenter frequency of the first signal and the frequency of the thirdsignal. And, modifying the frequency of the third signal based on thedifference signal to provide the carrier signal.

In another general aspect, innovative aspects of the subject matterdescribed in this specification can be embodied in a communicationdevice that includes one or more processors, a receiver coupled to theone or more processors, a transmitter coupled to the one or moreprocessors, and a data store coupled to the one or more processors. Thedata store includes instructions stored thereon which, when executed bythe one or more processors, causes the one or more processors to performoperations including receiving a first signal from a second device, thefirst signal including a carrier signal modulated with a firstmodulation signal. Detecting a frequency of the carrier signal byperforming a CAREX process on the first signal. Adding a secondmodulation signal to the carrier signal of the first signal to produce acombined signal, where the second modulation signal is a TM signal andthe first modulation signal is a non-TM signal. Transmitting thecombined signal. This and other implementations can each optionallyinclude one or more of the following features.

In some implementations, the device is a portable device. In someimplementations, the device includes a power source. In someimplementations, the power source can be one of a battery or a solarpower source.

Particular implementations of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. Implementations may increase the bandwidth ofsignals transmitted using traditional modulation schemes.Implementations may increase the data capacity for communicationchannels. Implementations may permit the combination of two differentlymodulated signals on a single carrier frequency. Some implementationsmay permit extraction of carrier signals from a modulated signal withlittle or no a priori information about the modulated signal. Someimplementations may be capable of extracting a carrier from a modulatedsignal without regard to the type of modulation used in the modulatedsignal. In other words, some implementations may able to extract carriersignals while being agnostic to the type modulation of an input signal.

The details of one or more implementations of the subject matterdescribed in this specification are set forth in the accompanyingdrawings and the description below. Other features, aspects, andadvantages of the subject matter will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C depict example systems in accordance with implementations ofthe present disclosure.

FIG. 2 depicts a block diagram of an example TM signal transmitter inaccordance with implementations of the present disclosure.

FIG. 3A depicts a block diagram of an example carrier extractor inaccordance with implementations of the present disclosure.

FIG. 3B depicts a block diagram of an example frequency detector inaccordance with implementations of the present disclosure.

FIGS. 4A and 4B depict example control signals generated by a carriersignal extraction device.

FIG. 5 depicts a block diagram of an example TM signal receiver inaccordance with implementations of the present disclosure.

FIG. 6A depicts a block diagram of an example TM signal separation andextraction device in accordance with implementations of the presentdisclosure.

FIG. 6B depicts frequency domain representations of signals at variousstages of the TM signal separation and extraction device shown in FIG.6.

FIGS. 7-9 depict example processes that can be executed in accordancewith implementations of the present disclosure.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

This specification relates to methods and systems for combiningtranspositional modulation (TM) signals with traditional modulation(non-TM) signals. More specifically, the specification relates tomethods and systems for receiving an existing non-TM signal and adding aTM signal to the carrier of the non-TM signal with minimal or nointerference to the non-TM signal. In addition, the specificationrelates to methods and systems for communications between devices usinga combined traditional modulation and TM signal on the same carriersignal. Although discussed in the context of TM, implementations of thepresent disclosure also may be applicable to other signal types.

Implementations of the present disclosure generally relate to methodsand systems for combining TM signals with traditional modulation(non-TM) signals. More specifically, implementations provide methods andsystems for receiving an existing non-TM signal and adding a TM signalto the carrier of the non-TM signal with minimal or no interference tothe non-TM signal. For example, an existing non-TM signal can bereceived by a TM capable communication device. The communication devicecan extract the carrier signal from the non-TM signal, modulate theextracted carrier with additional data using a TM signal, and combinethe TM signal with the received non-TM signal with minimal or nointerference to the non-TM signal.

Other implementations of the present disclosure generally extract acarrier signal from an existing modulated signal, modulate the extractedcarrier signal with a TM signal, and combine and retransmit the existingsignal with the TM signal on the same carrier signal. Specifically, theimplementations can extract a carrier frequency from a modulated signalin which the carrier signal has been suppressed (e.g., QPSK, QAM, APSK,BPSK). A CAREX (carrier extraction) circuit determines a frequencydifference between the frequency of the CAREX output signal and aweighted average of the carrier frequency of the input signal. Thecalculated difference value is used to continuously tune a signalgenerator to maintain a minimal difference between the weighted averageof the input carrier frequency and the CAREX output. The third harmonicof the extracted carrier is modulated with a data signal generating a TMmodulated signal. The TM modulated signal is heterodyned back to theextracted carrier frequency and combined with the existing modulatedsignal. The combined signal can then be transmitted. Moreover, the TMmodulated signal in the combined signal does not interfere with theexisting signal because the TM modulation is not recognized bydemodulation systems used to demodulate traditional modulation schemes.Instead, the TM signal appears as a slight increase in noise within theexisting signal.

Other implementations of the present disclosure generally receive acombined traditional modulation and TM signal on the same carrier signalthen separate the TM signal from the combined signal. Specifically, theimplementations can separate the existing signal from a combined signalincluding a traditionally modulated signal (the existing signal) and aTM modulated signal. The existing signal can be demodulated from thecarrier signal. An extracted carrier signal can be re-modulated with thedemodulated existing signal to re-create the existing signal alone,absent the TM modulated signal. The re-modulated existing signal can beremoved from the combined signal leaving only the TM modulated signalwhich can be demodulated using TM demodulation techniques describedherein.

As used herein the terms “Transpositional Modulation,” “TM modulation,”“TM,” and “TM signal” refer to a techniques of adding information to acarrier signal without affecting the amplitude, frequency or phase ofthe carrier signal (or a signal that is modulated according to such atechnique). More specifically, for example, the above terms refer to atype of modulation in which information is conveyed by altering (e.g.,transposing, time shifting) a harmonic of a carrier signal. For example,although the present disclosure is generally directed to producingTranspostional Modulation by altering the third harmonic of a carriersignal, in some implementations Transpostional Modulation can beproduced by altering other harmonics of a carrier signal (e.g., a fourthharmonic, fifth harmonic, sixth harmonic, etc.). Furthermore,Transpositional Modulation and/or TM signals are not detectable bytraditional de-modulators, for example, those used for amplitude,frequency, or phase modulated signals.

FIG. 1A depicts an example system 100 in accordance with implementationsof the present disclosure. The system 100 is a system of communicationdevices 102. The system 100 may be a radio frequency (RF) communicationsystem, a satellite communication system, a landline communicationsystem (e.g., a telephony or cable network), an optical communicationsystem, a computer network, or any other system of communication devices102. The communication devices 102 include systems for modulating acarrier signal with an information signal using traditional modulationtechniques and transmitting and receiving the modulated signal from onecommunication device 102 to/from another. For example, communicationdevice A may be a broadcast transmitter, communication device B may be asignal repeater, and communication devices C and D may be signalreceives. Traditional modulation techniques include, for example,amplitude modulation (AM), frequency modulation (FM), and phasemodulation (PM) in addition to complex modulation techniques thatincorporate aspects of AM, FM, and PM such as quadrature phase shiftkeying (QPSK), amplitude phase shift keying (APSK) and includingquadrature amplitude modulation (QAM). In addition, communicationdevices B and C include a TM transmitter 104 and a TM receiver 106. Insome examples, communication device C may be, for example, a passivereceiving device and may include a TM receiver 106 but not a TMtransmitter 104. In some examples, a TM transmitter 104 and/or a TMreceiver 106 can be integrated with traditional transmitters andreceivers. The TM transmitter 104 and/or TM receiver 106 can beimplemented as hardware devices (e.g., integrated circuits, chip-sets,application specific integrated circuits (ASIC), or field programmablelogic arrays (FPGA)) or they can be implemented in software (e.g., as asoftware defined radio (SDR)).

The system 100 can receive a traditionally modulated signal 108 andcombine the traditionally modulated signal 108 with a TM modulatedsignal 110 on the same carrier using a TM transmitter 104, therebyincreasing the overall bandwidth of the combined signal 112. The TMmodulated signal 110 can be separated from the combined signal 112 anddemodulated by a TM receiver 106. Likewise, the traditionally modulatedsignal 108 can be separately demodulated with no interference caused bythe TM modulated signal 110. This is possible because TM modulatedsignals are undecipherable by non-TM receivers, instead appearing as aslight increase of noise in traditionally modulated signals.

For example, communication device A may transmit a QAM signal 108 tocommunication device B. The TM transmitter 104 at communication device Bcan receive the QAM signal 108 and extract the carrier signal from theQAM signal 108. The TM transmitter 104 modulates the extracted carriersignal with a TM signal, combines the TM modulated signal 110 with theQAM signal 108, and retransmits the combined signal 112. In someexamples, as described below, the TM transmitter 104 can extract acarrier signal from a traditionally modulated signal 108 (e.g., the QAMsignal) in which the carrier is suppressed and while having little or noa priori information about the carrier signal (e.g., frequency or phaseinformation).

Communication devices C and D receive the combined signal 112. The TMreceiver 106 of communication device C separates and extracts the TMmodulated signal 110 from the combined signal 112, and then demodulatesthe TM modulated signal 110 to obtain the TM modulated data signal. Insome examples, as described below, the TM receiver 106 separates the TMmodulated signal 110 from the combined signal 112 by demodulatingtraditionally modulated signal 108 (e.g., the QAM signal), re-modulatingthe carrier with only the traditionally modulated signal 108, andsubtracting the re-modulated carrier signal from the combined signal 112leaving only the TM modulated signal 110. On the other hand,communication device D, which does not have a TM receiver 106, will onlydetect and demodulate the traditionally modulated signal 108; not the TMmodulated signal 110.

In some implementations, the carrier signal can be an intermediatefrequency (IF) carrier signal. That is, the carrier signal is notnecessarily at the same frequency of the carrier upon which the signalis ultimately be transmitted, but may be at an IF used internally withina system (e.g., a satellite communication system) as an intermediatestep in either signal transmission or reception. That is, in the case ofsignal transmission, a system may up-convert a combined signal 112 fromthe IF signal to a transmission carrier frequency prior to transmittingthe combined signal 112. Conversely, in the case of signal reception, asystem may down-convert a modulated signal from the transmission carrierfrequency to an IF frequency before separating the TM modulated signal110 from the combined signal 112. In other implementations, an IFcarrier signal may not be used, and the transmission carrier signal canbe modulated with both a traditionally modulated signal and a TMmodulated signal.

FIG. 1B depicts an example environment 130 for employing the techniquesdiscussed above. The example environment is described in the context ofa communication network for emergency response services (e.g., police,fire department, medical service personnel responding to an emergencysituation such as a natural disaster). It is appreciated, however, thatimplementations of the present disclosure can be realized in otherappropriate environments and contexts including, but not limited to, forexample, computer networks, broadcast networks, cablecast networks,satellite systems, internet of things (IoT) networks, etc.

The environment 130 includes a broadcast signal source 132 (e.g., abroadcast transmitter), a TM capable repeater station 134, and multipleuser communication devices 136 a-136 d, 138. The broadcast signal source132 can be, for example, a transmitter that transmits a non-TM modulatedsignal (e.g., such as communication device A of FIG. 1A). For example,the broadcast signal source 132 can be an FM or AM radio transmitter, atelevision transmitter, cablecast transmitter, a cellular servicetransmitter, or a radio frequency (RF) communications transmitter (e.g.,a high-frequency (HF) radio transmitter or repeater).

The user communication devices 136 a-136 d, 138 each include receiversfor receiving one or more types of non-TM modulated signals from thebroadcast signal source 134. For example, communication devices 136a-136 d, 138 can include, AM, FM, or satellite radios, digital radios,software radios (e.g., software defined radios (SDR)), smart phones,tablet computers, televisions with broadcast or cablecast receivers,citizen band (CB) radios, etc. Communication devices 136 a-136 b aredepicted as communication devices used by emergency service personnel.For example, communication device 136 a represents a radio system in anemergency service vehicle. Communication device 136 b represents atablet computer used by emergency service personnel. For example,communication device 136 b includes an SDR capable of receivingbroadcast radio or televisions signals. Communication devices 136 c, 136d represent communication systems in hospital or police dispatch centersor emergency action centers. For example, communication devices 136 c,136 d can include broadcast/cablecast televisions systems, AM/FM/digitalradio systems, and dispatch radio systems. In addition, communicationdevices 136 a-136 c each include a TM receiver (e.g., such ascommunication device C of FIG. 1A), and, in some examples, a TMtransmitter. Communication device 138 does not include a TM receiver(e.g., such as communication device D of FIG. 1A) and represents anon-emergency services communication device (e.g., radio, television,smartphone, SDR, etc.).

The TM capable repeater station 134 includes both non-TM and TMtransmitters and receivers (e.g., such as communication device B of FIG.1A). Repeater station 134 can receive non-TM broadcast signals 140,create a combined signal 142 by adding TM signals to the same carrier asthe non-TM signal, and transmit the combined signals 142 for receptionby user communication devices 136 a-136 d, 138. As discussed above,communication devices 136 a-136 d will be capable of detecting anddemodulating either or both the non-TM signals and the TM signals, whilecommunication device 138 will only be capable of detecting anddemodulating the non-TM signals.

The repeater station 134 can include, but is not limited to, a mobilerepeater station 134 a, an aerial repeater station 134 b, and a fixedrepeater station 134 c. For example, a mobile repeater station 134 a canbe transportable such that it can be readily deployed at a disasterscene. In addition, a mobile repeater station 134 a can include a localpower source (e.g., a battery, solar power source, a power generator).For example, a mobile repeater station 134 a can be implemented as ahandheld device, a “suitcase sized” device, or a truck/trailertransportable device. The size of the mobile repeater station 134 a maybe determined by the electronics required to obtain the desiredtransmission power of the device and size of a power source required forthe mobile repeater station 134 a. An aerial repeater station 134 b caninclude a repeater station that is attached to an aircraft or a drone.For example, an aerial repeater station 134 b can be deployable above adisaster area. For example, a fixed repeater station 134 c may be aprimary entry point (PEP) station for an emergency alert system (EAS).

For example, during an emergency, the repeater station 134 can embedinformation for emergency services personnel into broadcast signals 140from the broadcast signal source 132 using TM signals. The TM capablecommunication devices 136 a-136 d used by the emergency servicespersonnel will be able to detect and receive the information in the TMsignals, but non-TM capable communication devices 138 will not.

For example, during a large scale disaster (e.g., an earthquake)traditional communication channels can become overwhelmed and it may bedifficult to get much needed information to first responders anddispatchers. When an emergency occurs, the TM capable repeater stations134 can be used to provide additional communication channels foremergency service personnel without affecting the normal media contentthat is provided on existing channels (e.g. broadcast channels). Forexample, a repeater station 134 that is setup in response to anemergency can receive a broadcast signal 140 from a broadcast signalsource 132. For example, the broadcast signal 140 may be a radio stationsignal that includes a normally scheduled radio program or a specialnews alert. The repeater station 134 can add information for emergencyservice personnel to the broadcast signal 140 without affecting thecontent contained in the non-TM broadcast signal 140. For example, theinformation added to the broadcast signal 140 can include but is notlimited to, audio data, image data, text data, and video data.Furthermore, the repeater station 134 can distribute information tocoordinate first responders (e.g., deployment instructions, locations ofdisaster scenes, routing information around blocked streets, etc.) andinformation to aid dispatchers (e.g., on scene status reports, aerialimages or video of disaster scenes, e.g., from an aerial repeaterstation 134 b) in the TM signals.

In some implementations, a mobile repeater station 134 a can be setup ata disaster scene to distribute information from the scene. For example,a mobile repeater station 134 a can be setup at the site of a collapsedroadway. The mobile repeater station 134 a can be tuned to a local FMradio station (a broadcast signal 140). On site personnel 146 can usethe mobile repeater station 134 a to transmit images from the scene to anearby dispatch center (e.g., a communication device 136 c at a hospitaland/or fire station) and to EMS teams (e.g., communication devices 136a, 136 b) that are enroute to the scene. For example, the mobilerepeater station 134 a can receive data for transmission in TM signalsfrom a communication device 144 at the scene. On site personnel 146 cancapture images and/or video of the scene with a communicating device 144(e.g., a smartphone or tablet computer) and transfer the images and/orvideo to the repeater station 134 a. Communications between the on scenecommunication device 144 and the repeater station 134 a need not use TMmodulation, but can be accomplished using either non-TM signal or TMsignals. Furthermore, the communications between the on scenecommunication device 144 and the repeater station 134 a can be wired orwireless. The repeater station 134 a receives the data (e.g., imagesand/or video) from the on scene communication device 144 and encodes thedata in a TM signal that is added to FM radio station broadcast signal140 to create a combined signal 142. The repeater station 134 a thentransmits the combined signal 142.

Each of the communication devices 136 a-136 d, 138 may receive thecombined signal 142, but only TM capable communication devices 136 a-136d will be able to detect and demodulate the TM portion of the combinedsignal 142. For example, the communication device 138, which is not TMcapable, tuned to receive the broadcast signal 140 will detect only thebroadcast signal 140 included in the combined signal 142. Thus, the TMsignal containing information from the first responders will not affectthe music or news report that a driver is listening to on communicationdevice 138 (e.g., a car radio). At the same time, communication device136 c (e.g., a dispatch system at a hospital) will be able to detect anddemodulate the TM portion of the combined signal 142. Thus, hospitalpersonnel will be able to receive and view the images from the disasterscene. The hospital personnel can then, for example, make more informeddecisions as to the type and extent of injuries that the firstresponders are dealing with. This information can also be used to aid indetermining the number of additional first responders needed, the typeof equipment needed, and how to prepare the hospital to receive theinflux of patients. Moreover, such on scene information can be receivedfrom multiple mobile repeater devices 134 a at multiple disaster scenesto help prioritize medical resources.

In another example implementation, an aerial repeater station 134 b canbe flown over a disaster scene and/or surrounding areas. As with themobile repeater station 134 a, the aerial repeater station 134 b can betuned to a local FM radio station (a broadcast signal 140). The aerialrepeater station 134 b can capture areal images or video of the scenefor transmission in the TM portion of a combined signal 142. Forexample, the repeater station 134 b can receive the aerial data (e.g.,images and/or video) from a camera on the aircraft and encode the datain a TM signal that is added to FM radio station broadcast signal 140 tocreate a combined signal 142. The repeater station 134 b then transmitsthe combined signal 142. As noted above, each of the communicationdevices 136 a-136 d, 138 may receive the combined signal 142, but onlyTM capable communication devices 136 a-136 d will be able to detect anddemodulate the TM portion of the combined signal 142.

In another example implementation, a fixed repeater station 134 c can beused to send information to emergency service personnel. For example, afixed repeater station 134 c can be used in a manner similar to thatdiscussed above in reference to the mobile repeater station 134 a. Forexample, a fixed repeater station 134 c can be tuned to a radio ortelevision station that is transmitting an emergency broadcast signal140 (e.g., an Emergency Alert System (EAS) message). The fixed repeaterstation 134 c can receive additional information for emergency servicepersonnel and encode the information for the emergency service personnelin a TM signal to be transmitted in a combined signal 142 along with theemergency broadcast signal 140. Communication devices 136 c, 136 d(e.g., televisions used in hospitals, fire stations, and policestations) can be equipped to detect and decode the TM signals. Thus,when an emergency broadcast signal is received such communicationdevices 136 c, 136 d can display not only the emergency broadcast signal140 but also information pertinent to the emergency service personnel.For example, dispatch orders or blocked routes to a disaster scene canbe included in the TM signals and presented to the emergency servicepersonnel. In some implementations, for example if the fixed repeaterstation 134 c is a PEP station for the EAS, the fixed repeater station134 c may not receive a broadcast signal 140 from a separate broadcastsignal source 132, but can generate both the non-TM modulation signalfor the emergency broadcast signal and the TM modulation signal for theinformation specific to the emergency service personnel. In other words,the fixed repeater station 134 c may not add the TM signal to anexisting non-TM broadcast signal, but can generate and transmit both thenon-TM and TM portions of the combined signal 142.

FIG. 1C depicts another example environment 150 for employing thetechniques discussed above. The example environment is described in thecontext of a communication network for a sports venue (e.g., aracetrack). Again, it is appreciated that implementations of the presentdisclosure can be realized in other appropriate environments andcontexts.

The environment 150 depicts several vehicles 152 each havingcommunication equipment (e.g., radios), pit crews 154 with pit crewcommunication equipment 160, and race fans 156. In addition, theenvironment 150 depicts a broadcast signal source 158 (e.g., a broadcasttransmitter). The broadcast signal source 158 can be, for example, atransmitter that transmits a non-TM modulated signal (e.g., such ascommunication device A of FIG. 1A). For example, the broadcast signalsource 158 can be an FM or AM radio transmitter broadcasting the race atthe race track.

In some implementations, a sports venue (e.g., racetrack, sports stadiumor arena) can use TM capable devices to provide fans with uniqueentertainment experiences while watching a sporting event. For example,a racetrack may provide fans 156 with the opportunity to listen tocommunications 174 between their favorite driver and the driver's pitcrew. For example, fans 156 a can rent a TM capable receiver device 161for use at the racetrack. The pit crew's 154 a communication equipment160 a can include a TM capable transmitter and receiver. In accordancewith the processes described above in reference to FIG. 1A, thecommunication equipment 160 a can add the communications 174 between thedriver of vehicle 152 a and pit crew 154 a to a broadcast signal 170(e.g., a radio broadcast of the race). For example, the communicationequipment 160 a can encode the communications 174 in a TM signal and addthe TM signal to the broadcast signal 170 to produce combined signal172. Accordingly, only the TM capable receiver devices 161 will be ableto detect and demodulate the TM signals containing the driver/pit crewcommunications 174. Thus, only fans 156 a who rent the receiver devices161 will be able to listen to the driver/pit crew communications 174.

In some examples, the TM capable receivers 161 can be implemented as amobile application for execution on the fans' 156 a mobile device (e.g.,smartphone). For example, the TM capable receivers 161 can beimplemented as SDRs. In some examples, the broadcast signal 170 may be aWiFi signal and the broadcast transmission source 158 can be WiFi accesspoints within the sports venue. In such implementations, the TM signalsincluding the driver/pit crew communications 174 can be added to theWiFi signal. For example, the communication equipment 160 can add the TMsignals including the driver/pit crew communications 174 can be added tothe WiFi signal. In some examples, the WiFi access points can include TMcapable transmitters. For example, the driver/pit crew communications174 can be sent through a computer network at the venue and the WiFiaccess points can encode the communications 174 in a TM signal and addthe TM signal to the non-TM WiFi signals transmitted by the WiFi accesspoint.

In another example implementation, a TM capable radio within a vehicle152 b (e.g., racecar) can be used to add information associated with thevehicle to the radio communications between the vehicle driver and a pitcrew 154 b. For example, using the processes described above inreference to FIG. 1A, a TM capable radio within a vehicle 152 b can adda TM signal including the vehicle information to the radio communicationsignals 176 transmitted between the vehicle 152 b and the pit crew'scommunication equipment 160 b. For example, a TM capable radio can add aTM signal with vehicle diagnostic information to the carrier used forthe radio signals 176 to produce the combined signal 178. Thecommunication equipment 160 b can also include a TM capable receiver todetect and demodulate the TM signals. Accordingly, the vehiclesdiagnostic information can be transmitted to the pit crew 154 b withoutaffecting the radio communications signals 176. For example, thecommunication equipment 160 b can include a computer and a display fordisplaying the diagnostic information to the pit crew 154 b. Vehiclediagnostic information can include, but is not limited to, engine data(e.g., temperatures, fluid levels, RPM), tire pressures, tiretemperatures, break temperatures, a video feed from the vehicle, etc.

Although described in reference to racecars, TM signals and TM capableradios (e.g., communication radios or other types of signaltransmitters/receivers) can be implemented to convey vehicle data inother contexts as well. For example, additional contexts can include,but are not limited to, shipping vehicles (e.g., trucks, trains, ships,aircraft), emergency service vehicles (e.g., law enforcement vehicles,ambulances, fire department vehicles), self-driving vehicles,agricultural vehicles (e.g., tractors and harvesting equipment such ascombines), and traffic signal preemption systems (e.g., used byemergency service vehicles). In such contexts, the vehicle data caninclude location information (e.g., GPS data), vehicle identification,course, speed, cargo information, shipping origin, shipping destination,etc. Furthermore, TM cable vehicle radios can include, but are notlimited to, communication radios (e.g., CB radios, bridge-to-bridgeradios (ships)), automatic identification system (AIS) maritimetransmitters, etc.

FIG. 2 depicts a block diagram of an example TM signal transmitter 104in accordance with implementations of the present disclosure. The TMtransmitter 104 includes a carrier extraction portion (CAREX 206), aharmonic generation portion 202, a TM modulating portion 204, and aheterodyning portion 205. The carrier extraction portion includes thecarrier extractor (CAREX) 206. The harmonic generation portion 202includes a second harmonic generator 208 and a third harmonic generator210. The TM modulating portion 204 includes a signal optimizer 212 and aTM modulator 214. And, the heterodyning portion 205 includes a signalmixer 216, a bandpass filter 218, and a power amplifier 220. Inaddition, the TM transmitter 104 includes a signal coupler 222 and asignal combiner 224.

In operation, the TM transmitter 104 receives an existing modulatedsignal (e.g., traditionally modulated signal 108 of FIG. 1). The signalcoupler 222 samples the existing modulated signal and passes the sampleof the existing modulated signal to the CAREX 206. The CAREX 206extracts a carrier signal (f_(c)) from the existing modulated signal.The CAREX 206 is described in more detail below in reference to FIGS.3A-4B. The output of the CAREX 206 is a pure sinusoidal signal at thefundamental frequency of the carrier from the existing modulated signal.In some examples, the CAREX 206 is agnostic to the type of modulationused in the existing modulated signal. That is, the CAREX 206 canextract the carrier signal from an existing modulated signal regardlessof the type of modulation used in the existing modulated signal. In someexamples, the CAREX 206 can extract carrier signals even when thecarrier is suppressed in the existing modulated signal, and can do sowith little or no a priori information about existing modulated signal'scarrier (e.g., frequency or phase modulation information).

The CAREX 206 passes the extracted carrier signal to a second harmonicsignal generator 208 and a third harmonic signal generator 210, whichgenerate signals at the second and third harmonic frequencies (2 f _(c)and 3 f _(c) respectively) of the fundamental carrier frequency (f_(c)).The second and third harmonic signals (2 f _(c), 3 f _(c)) are used bythe TM modulation portion 204 and the heterodyning portion 205 of the TMtransmitter 104 to generate a TM modulated signal and to heterodyne theTM modulated signal to the fundamental carrier frequency (f_(c)).

The TM modulation portion 204 of the TM transmitter 104 modulates thethird harmonic (3 f _(c)) of the carrier signal (f_(c)) with a datasignal to generate the TM modulated signal. The TM modulated signal isthen heterodyned to the frequency of the carrier signal (f_(c)),combined with the existing modulated signal, and outputted to an antennafor transmission.

In more detail, TM modulation portion 204 receives a data signal fortransmission (e.g., a baseband (BB) data signal). The data signal isoptionally processed for transmission as a TM modulated signal by thesignal optimizer 212. In some examples, the signal optimizer 212produces an optional pattern of inversion and non-inversion of themodulating signal, and filters the modulating signal to ensure that thetotal bandwidth of the data signal is within the channel bandwidth ofthe existing modulated signal. In some examples, the signal optimizer212 can include sample-and-hold circuitry and filters to prepare themodulating signal for transmission as a TM modulated signal. In someexamples, the signal optimizer 212 can be bypassed or turned off and on.

The TM modulator 214 modulates the third harmonic (3 f _(c)) of thecarrier signal (f_(c)) with a data signal to generate the TM modulatedsignal. For example, the TM modulator 214 modulates the third harmonic(3 f _(c)) by introducing a variable time delay based on the datasignal. In other words, the TM modulator 214 can use the data signal asa control signal for introducing an appropriate time delay to thirdharmonic (3 f _(c)). As such, an amount of time delay introduced intothe third harmonic (3 f _(c)) represents discrete bits or symbols of thedata signal. The described time delay modulation technique may beconsidered as time-shift modulation and is performed on the thirdharmonic (3 f _(c)) of the intended carrier frequency (3 f _(c)).

The time-shift modulation of the third harmonic (3 f _(c)) produces asingle set of upper and lower Bessel-like sidebands. The inventor hasconfirmed such results in laboratory simulations with an oscilloscopeand spectrum analyzer. Moreover, the bandwidth of these sidebands can belimited to the bandwidth of an intended communication channel by theoptimizer 212 before TM modulation of the signal, as described above.

In some examples, the time delay may be a phase shift. However, thetime-shift modulation described above is not equivalent phasemodulation. As noted above, the inventor has confirmed in laboratorytests that the time-shift modulation only produces a single pair ofupper and lower Bessel-like sidebands. Phase modulation, however,produces a series upper and lower Bessel-like sidebands.

The heterodyning portion 205 prepares the TM modulation signal do becombined with the existing modulated signal and transmitted by thereceiver. The TM modulated signal is then heterodyned (e.g., frequencyshifted) by mixer 216 down to the fundamental frequency of the carriersignal (f_(c)). The mixer 216 multiplies the TM modulated signal withthe second harmonic of the carrier (2 f _(c)) which shifts the TMmodulated signal to both the fundamental carrier signal frequency(f_(c)) and the fifth harmonic frequency of the carrier. The bandpassfilter 218 removes signal at the fifth harmonic frequency as well as anyadditional signals or noise outside of the bandwidth of the TM modulatedsignal centered at the fundamental carrier signal frequency (f_(c)).

The TM modulated carrier signal is amplified by power amplifier 220 andcombined with the existing modulated signal by the signal combiner 224.It may be necessary, in some examples, to adjust the phase of the TMmodulated carrier signal to match the phase of the carrier in theexisting modulated signal before combining the two signals andtransmitting the combined signal.

FIG. 3A depicts a block diagram of an example CAREX 206 in accordancewith implementations of the present disclosure. The CAREX 206 can beimplemented as a circuit in a device such as a TM transmitter or TMreceiver, for example. In some implementations, the CAREX 206 can beimplemented as a standalone device for installation into in a largersystem (e.g., an application specific integrated circuit (ASIC) or fieldprogrammable logic array (FPGA)). In some implementations, the CAREX 206can be implemented in software, for example, as a set of instructions ina computing device or a digital signal processor (DSP).

The CAREX 206 operates by determining a center frequency of an inputsignal (e.g., either modulated or unmodulated), comparing the centerfrequency to the frequency of a pure sinusoidal signal produced by asignal generator to create a error signal, and adjusting the frequencyof the signal generator output signal based on a control signalgenerated from the error signal until the error signal is minimized.Furthermore, the CAREX 206 does not require a priori information about acarrier signal to extract the carrier signal and can extract carriersignals when the carrier of the modulated signal is suppressed.

The CAREX 206 includes amplitude limiters 302 a, 302 b, filters 304 a,304 b, frequency detectors 306 a, 306 b, signal generator 308,difference circuit 310, and an amplifier 312. The amplitude limiter 302a and filter 304 a condition input signal before the input signal isanalyzed by the first frequency detector 306 a. The amplitude limiter302 a removes any variations in the amplitude of the input signal. Inother words, the amplitude limiter 302 a stabilizes the amplitude of theinput signal. In some examples, the amplitude limiters 302 a, 302 b canbe an analog comparator or an automatic gain control (AGC) circuit. Thefilters 304 a, 304 b are bandpass filters and removes extraneous signals(e.g., harmonics) and noise outside the channel bandwidth of the inputsignal.

The frequency detectors 306 a and 306 b can be frequency discriminatorsor quadrature detectors. The first frequency detector 306 a detects thecenter frequency of the input signal. As shown in the frequency domainplot 320, an input signal produced by traditional modulation techniquesgenerally has symmetric sidebands 322 located on either side of thecarrier frequency 324. The frequency detector 306 a can determine acenter frequency of an input signal based on, for example, thefrequencies of the outer edges of the sidebands 322. Furthermore, thefrequency detector 306 a can use the sidebands 322 of an input signal todetermine the center frequency even if the carrier signal 324 issuppressed, as illustrated by the dotted line.

The signal generator 308 generates a pure sinusoidal signal (e.g., asingle frequency signal) which is provided to a second frequencydetector 306 b. The signal generator 308 can be, for example, a voltagecontrolled oscillator (VCO) such as, but not limited to, a voltagecontrolled LC (inductor-capacitor) oscillator circuit, a voltagecontrolled crystal oscillator (VCXO), or a temperature-compensated VCXO.The second frequency detector 306 b detects the frequency of the outputsignal from the signal generator 308. In some examples, the outputsignal from the signal generator 308 is provided to an amplitude limiter302 b and filter 304 b before being transmitted to the second frequencydetector 306 b. The amplitude limiter 302 b and filter 304 b stabilizeand filter the amplitude of the signal generator output signal similarto amplitude limiter 302 a and filter 304 a.

The output from each of the first and second frequency detectors 306 a,306 b is provided as inputs to the differencing circuit 310. The outputof both the first and second frequency detectors 306 a, 306 b can be, insome examples, a direct current (DC) voltage signal representing thecenter frequency of the input signal and the frequency of the signalgenerator 308 output signal, respectively. The output of the differencecircuit 310 is a error signal representing the difference in frequencybetween the center frequency of the input signal in the signal generatoroutput signal. The error signal (e.g., a DC voltage) is amplified byamplifier 312 and provided as a control signal to the signal generator308. The amplifier 312 can be, for example, a high gain integratingcircuit that integrates the inputted error signal over time to producethe control signal.

The signal generator 308 adjusts the frequency of its output signalbased on the control signal until the frequency of the signal generator308 output is matched to the center frequency of the input signal. TheDC value of the control signal is used to control the frequency of thesignal generator output, as shown in FIG. 4B and described below. Thesignal generator output is provided as the output of the CAREX 206.Frequency domain plot 330 and time domain plot 334 represent an exampleCAREX 206 output signal. As shown, the output signal of the CAREX 206 isa pure sinusoidal signal having a frequency 332 equivalent to thefundamental carrier frequency of the input signal.

In some implementations, the frequency detectors 306 a and 306 b arematched. In some examples, the matched frequency detectors 306 a and 306b have similar frequency to DC output characteristics over changingmodulated input frequencies. In some examples, the matched frequencydetectors 306 a and 306 b have similar thermal and aging properties. Insome examples, the amplitude limiters 302 a and 302 b, and the filters304 a and 304 b are matched.

In some examples, when the error signal is minimized the signalgenerator output is effectively matched to the center frequency of theinput signal. For example, the error signal can be considered asminimized when its magnitude is zero or substantially close to zero(e.g., when the control signal has a magnitude that is negligible inrelation signal magnitudes measureable or usable by components of theCAREX 206). In some examples, the error signal is considered to beminimized when its magnitude is below a threshold value (e.g., an errortolerance threshold).

In some implementations, the CAREX 206 is adapted to extract carrierfrequencies from single sideband signals. In some examples, the CAREX206 includes a controller that offsets the output signal of the signalgenerator 308 by an appropriate offset frequency. For example, theoutput of the frequency generator 308 can be offset after it is fed backto the second frequency detector 306 b, so as to not adversely affectthe control signal. In some examples, the first frequency detector 306 acan be configured to determine a frequency offset based on the bandwidthof the input signal. In such examples, the first frequency detector 306a can adjust the detected frequency by the frequency offset.

FIG. 3B is a block diagram of an example frequency detector 306 inaccordance with implementations of the present disclosure. The frequencydetector 306 illustrated in FIG. 3B is an example quadrature-baseddetector circuit. The frequency detector 306 includes a phase shiftnetwork 350, a signal mixer 352, and a filter 354. The phase shiftnetwork 350 is a frequency sensitive circuit, such as an all passfilter, for example, that causes a phase shift in an input signal thatcorresponds with the frequency of the input signal. In other words, thephase shift network 350 causes a change in the phase angle of the inputsignal relative to the frequency of the input signal. In some examples,the phase shift network 350 is tuned to produce a nominal phase shift of90 degrees (e.g., quadrature to the input signal) for a nominal designfrequency (e.g., a 70 MHz IF for a communication system).

The signal mixer 352 can be, for example, a signal multiplier. Thesignal mixer 352 receives the input signal and an output signal from thephase shift network 350 as inputs. The filter 354 is a low pass filter.

Plot 360 shows example signals at various points in the frequencydetector 306. The input signal (Signal A) is passed to the phase shiftnetwork 350 and the signal mixer 352. Signal A is shown as a sinusoidfor simplicity, however, Signal A can be a modulated signal. Signal B isthe output of the phase shift network 350 and is phase shifted relativeto the input signal (Signal A). The value of the phase shift correspondsto the frequency of Signal A, and is nominally 90 degrees for a designfrequency. Deviations from the design frequency resulting in a phaseshift of Signal B that deviates from the nominal 90 degrees. The inputsignal (Signal A) is mixed with the output of the phase shift network350 (Signal B) to produce Signal C (e.g., Signal C=Signal A×Signal B).Signal C has a DC offset component corresponding to the phase differencebetween Signals A and B, and by extension, to the frequency of Signal A.The low pass filter 354 then removes the high frequency components ofSignal C leaving only the DC component (Signal D). The deviation ofSignal B's phase shift from the a nominal 90 degrees is exaggerated inplot 360 in order to clearly show the resulting DC output signal (SignalD).

FIG. 4A depicts a plot 400 of an example control signal 402 generated inan example CAREX 206. The plotted control signal 402 is an example ofthe input signal to the signal generator 308 of FIG. 3A. The plottedcontrol signal 452 is broken into several regions (406-410). The regionsillustrate a variations 404 in the control signal 402 as the inputsignal to the CAREX 206 is switched between several different inputsignals, each modulated using a different type of modulation. The inputsignal in region 406 is a QPSK modulated signal. The input signal inregion 408 is a QAM modulated signal. The input signal in region 410 isan unmodulated carrier signal. Each of the input signals in regions406-410 is applied to a 70 MHz carrier. The plot 400 illustrates therobustness of the CAREX 206 and its adaptability to extracting carriersignals from various input signals without regard to the types ofmodulation applied to the carrier signal.

FIG. 4B depicts a plot 450 of another example control signal 452generated in an example CAREX 206. The plotted control signal 452 is anexample of the input signal to the signal generator 308 of FIG. 3A. Theplotted control signal 452 is broken into several regions (456-460). Theregions illustrate transitions 454 of the control signal 452 as theinput signal to the CAREX 206 is switched between several differentinput signals, each having a different carrier frequency. The inputsignal in region 456 is a 67 MHz carrier signal. The input signal inregion 458 is a 73 MHz carrier signal. The input signal in region 460 isa 70 MHz carrier signal. The plot 450 illustrates the robustness of theCAREX 206 and its adaptability to extracting different frequency carriersignals. In some implementations, as shown, the CAREX 206 loop can bedesigned for a specific center frequency (e.g., 70 MHz as shown). Forexample, the design center frequency can be a specific carrier frequencyor IF of a communication system such as a satellite or radio frequency(RF) communication system, for example.

FIG. 5 depicts a block diagram of an example TM signal receiver 106 inaccordance with implementations of the present disclosure. The TMreceiver 106 includes a carrier extraction portion (e.g., CAREX 506), aharmonic generation portion 504, a signal separation and extractionportion (SEPEX) device 512, and a TM demodulator 514. As in the TMtransmitter 104, the harmonic generation portion includes a secondharmonic generator 508 and a third harmonic generator 510. In addition,the TM receiver 106 can include a signal splitter 502 to split acombined input signal (e.g. combined signal 112 of FIG. 1) between theTM receiver 106 and a signal receiver for traditional modulated signals.

In operation, the TM receiver 106 receives a combined input signal andprovides the combined signal to both the CAREX 506 and SEPEX device 512.As described above in reference to the TM receiver 106, the CAREX 506extracts a carrier signal (f_(c)) from the combined signal, and thesecond harmonic generator 508 and third harmonic generator 510,respectively, generate second and third harmonics (2 f _(c) and 3 f_(c)) of the extracted fundamental carrier frequency (f_(c)). Both thecarrier signal (f_(c)) and second harmonic signal (2 f _(c)) areprovided to the SEPEX device 512. The third harmonic signal (3 f _(c))is provided to the TM demodulator 514.

The TM demodulation portion 504 separates and extracts the traditionallymodulated signal from the combined signal to obtain the TM modulatedsignal. The SEPEX device 512 provides the TM modulated signal to the TMdemodulator 514, which, demodulates the TM modulated signal to obtain abaseband data signal. The SEPEX device 512 separates and extracts the TMmodulated signal from the combined signal. In some implementations,before outputting the TM modulated signal, the SEPEX device 512heterodynes (e.g., up-shifts) the TM modulated signal to the thirdharmonic frequency (3 f _(c)) for demodulation. The SEPEX device 512 isdescribed in more detail below in reference to FIG. 6.

The TM demodulator 514 uses the third harmonic signal (3 f _(c))provided by the third harmonic generator 210 as a reference signal forTM demodulation. The TM demodulator 514 demodulates the TM signal bysensing the time shifts between TM modulated carrier signal from theSEPEX device 512 and the third harmonic signal (3 f _(c)). In someexamples, the TM demodulator 514 can be a phase detection circuit. Insome implementations, the TM demodulator 514 detects the time shifts bydetermining a correlation between the TM modulated carrier signal andthe third harmonic signal (3 f _(c)) based on, for example, a product ofthe two signals.

FIG. 6A depicts a block diagram of an example TM signal SEPEX device 512in accordance with implementations of the present disclosure. The SEPEXdevice 512 can be implemented as a circuit in a device such as a TMreceiver, for example. In some implementations, the SEPEX device 512 canbe implemented as a standalone device for installation into in a largersystem (e.g., an application specific integrated circuit (ASIC) or fieldprogrammable logic array (FPGA)). In some implementations, the SEPEXdevice 512 can be implemented in software, for example, as a set ofinstructions in a computing device or a digital signal processor (DSP).

In operation, the SEPEX device 512 demodulates the traditionallymodulated signal from the combined signal. Because the TM modulation isnot detected by traditional signal demodulation, the resulting signaldoes not include the TM signal, but only the demodulated data signalfrom the traditional modulation signal. A “clean” (e.g., un-modulated)carrier is then re-modulated with the previously demodulated data signalfrom the traditional modulation signal. The SEPEX 512 computes thedifference between the combined signal and the re-modulated signal toobtain a TM modulated carrier signal. In other words, the SEPEX device512 removes a traditionally modulated signal from the combined signal bydemodulating the traditionally modulated signal, re-modulating a “clean”(e.g., un-modulated) carrier, and subtracting the re-modulated signalfrom the combined signal, thereby, leaving only the TM modulatedcarrier.

The SEPEX device 512 includes a signal demodulator 602, a signalmodulator 604, low-pass filters 606 a, 606 b, a summing circuit 608, adifference circuit 610, a delay circuit 612, a mixer 614, a bandpassfilter 616, and an amplitude limiter 618. The demodulator 602 is anon-TM signal demodulator, and the modulator 604 is a non-TM signalmodulator. That is, the demodulator 602 and modulator 604 aretraditional modulation type (e.g., AM, FM, PM, QAM, APSK, etc.)demodulator and modulator. The demodulator 602 and modulator 604 aredepicted as a complex (e.g., quadrature and in-phase) demodulator andmodulator, however, in some examples the demodulator 602 and modulator604 can be a simple (e.g., single phase) demodulator and modulator.

The operation the SEPEX device 512 is described below in more detail andwith reference to FIGS. 6A and 6B. FIG. 6B depicts frequency domainrepresentations of signals (A-F) at various stages of the SEPEX device512. The demodulator 602 receives the combined signal (A) (e.g. combinedsignal 112 of FIG. 1) as one input, and the carrier signal (f_(c)) fromthe CAREX 506 as a second input. The combined signal includes both atraditionally modulated signal and a TM modulated signal. As shown bysignal (A) in FIG. 6B, the combined signal includes frequency contentfrom both the TM modulated signal and the traditionally modulated signalcentered about the carrier frequency (f_(c)). The demodulator 602demodulates the traditional modulated signal from the combined signalproducing a baseband data signal. As noted above, because the TMmodulation is not detected by traditional signal demodulation, theresulting baseband data signal does not include a TM signal.

In the case of complex modulation, the demodulator 602 demodulates boththe in-phase and quadrature phase of the combined signal producing anin-phase and a quadrature phase baseband data signal. The low-passfilters 606 a and 606 b remove any extraneous signals or noise from thebaseband data signals, for example, harmonics introduced by thedemodulation process. The resulting baseband data signal, shown bysignal (B), includes only the frequency content from the traditionallymodulated signal centered at zero frequency (baseband). Morespecifically, a TM modulated signal does not exist at baseband, andthus, the TM modulated signal is removed by converting the traditionallymodulated signal to baseband.

The modulator 604 receives the baseband data signals (e.g., in-phase andquadrature phase signals) as a first input, and the carrier signal(f_(c)) from the CAREX 506 as a second input. The modulator 604re-modulates the un-modulated carrier signal (f_(c)) from the CAREX 506with the baseband data signals resulting in re-modulated carriers(re-modulated in-phase and quadrature phase carriers) having only thetraditionally modulated signal. The in-phase and quadrature phasere-modulated carriers are combined by the summing circuit 608 (signal(C)). FIG. 6B signal (C) shows the re-modulated signal again centeredabout the carrier frequency (f_(c)). In some examples, the carriersignal (f_(c)) may be phase shifted or delayed to account for delaysintroduced into the baseband data signals during the demodulation andfiltering process. This is to ensure that the resulting re-modulatedsignal is in phase with the combined signal.

The re-modulated signal is subtracted from the combined signal by thedifference circuit 610 removing the traditionally modulated signal fromthe combined signal. The resulting signal, show by signal (D), includesonly the TM modulated carrier signal (f_(c)). The combined signal isdelayed by the delay circuit 612 to account for delays introduced intothe re-modulated signal by the demodulation and re-modulation process.

The TM modulated signal is heterodyned (e.g., up-shifted) to the thirdharmonic (3 fc) by the mixer 614. The mixer 614 multiplies the TMmodulated signal with the second harmonic (2 f _(c)) of the carrier fromthe second harmonic generator 508 producing signal (E). Heterodyning theTM modulated carrier signal (f_(c)) with the second harmonic (2 fc)shifts the TM modulated signal to both the third harmonic (3 fc) and thenegative carrier frequency (−fc) (e.g., a phase inverted version of theTM modulated signal at the carrier frequency). The bandpass filter 616removes the phase inverted TM signal at the carrier frequency leavingonly the TM modulated third harmonic (3 fc) (signal (F)), and theoptional amplitude limiter 618 removes any variations in the amplitudeof the TM modulated third harmonic signal.

In some examples, the SEPEX device 512 can include multiple differenttypes of demodulators 602 and modulators 604. For example, the SEPEXdevice 512 can include FM, PM, and QAM demodulators 602 and modulators604. In such examples, the SEPEX device 512 can also include a controldevice that detects the type of traditional modulation on input signal,and sends the input signal to the appropriate set of demodulator andmodulator.

Although the SEPEX device 512 is described in the context of separatingand extracting a TM modulated signal from a traditionally modulatedsignal, in some implementations, the SEPEX device 512 can be modified toseparate two traditionally modulated signals such as separatingnon-quadrature modulated signals (e.g., in-phase modulated signal) andquadrature modulated signals. For example, a non-quadrature modulatedsignal could be separated and extracted from a combined I/Q modulatedsignal by modifying the SEPEX device 512 shown in FIG. 6A such that onlythe quadrature modulated signal is demodulated and demodulated bydemodulator 602 and modulator 604.

FIG. 7 depicts an example process 700 for adding information to existingcommunication signals that can be executed in accordance withimplementations of the present disclosure. In some examples, the exampleprocess 700 can be provided as computer-executable instructions executedusing one or more processing devices (e.g., a digital signal processor)or computing devices. In some examples, the process 700 may be hardwiredelectrical circuitry, for example, as an ASIC or an FPGA device. In someexamples, the process 700 may be executed by a software defined radio(SDR).

A first signal including a carrier signal modulated with anon-transpostional modulation (TM) signal is received (702). Forexample, the first signal can be a broadcast signal transmitted by abroadcast transmitter. For example, a broadcast signal can be an AM orFM radio signal, a broadcast or cable cast televisions signal, asatellite communication signal (e.g., a satellite television signal, aGPS signal). In some examples, the first signal is received by acommunication device that includes both traditional and TM receivers andtransmitters.

A frequency of the carrier signal is detected by performing a carrierextraction process (CAREX) on the first signal (704). For example, aCAREX process such as that described in reference to FIGS. 3A-4B and 8can be performed on the first signal to extract the frequency of thecarrier signal from the first signal.

A TM signal is added to the carrier signal of the first signal toproduce a combined signal (706), and the combined signal is transmitted(708). The combined signal may be received by various differentreceivers, but only TM capable receivers will be able to detect that theTM signal is present in the combined signal. For example, the TMmodulation signal can be used to carry specialized data for emergencyservice personnel. The TM signal can be used to expand the data ratethrough a given communications channel during an emergency situation. Insome examples, the TM signal can be used to add supplementaryinformation to communication signals.

In some implementations, a TM signal is added to a carrier signal bymodulating a harmonic of the carrier signal (e.g., a third harmonic)with a data signal. The modulated harmonic is heterodyned to thefrequency of the carrier signal. For example, the modulated harmonic canbe heterodyned to the frequency of the carrier signal by mixing it withanother appropriate harmonic (e.g., a second harmonic) of the carriersignal. In some examples, a harmonic of the carrier signal is modulatedwith data by transposing or time shifting the third harmonic torepresent data from the data signal (e.g., data bits or symbols).

In some implementations, the phase of the first signal and the secondsignal are synchronized before generating the combined signal. Forexample, the phase of a TM modulated signal can be synchronized withthat of a received non-TM signal before combining the two signals andtransmitting the combined signal. In some examples, the phase of thecarrier of the TM signal can be phase matched with the carrier signal ofthe non-TM signal before the two signals are combined.

FIG. 8 depicts an example process 800 for extracting a carrier frequencyfrom an input signal that can be executed in accordance withimplementations of the present disclosure. In some examples, the exampleprocess 800 can be provided as computer-executable instructions executedusing one or more processing devices (e.g., a digital signal processor)or computing devices. In some examples, the process 800 may be hardwiredelectrical circuitry, for example, as an ASIC or an FPGA device. In someexamples, the process 800 may be executed by an SDR.

A center frequency of an input signal is detected (802). For example,the center frequency can be detected based on frequency side lobes ofthe input signal. In some examples, the input signal can include thecarrier signal modulated with the modulation signal. In some examples,the input signal is a carrier signal modulated with a traditionalmodulation signal and a TM modulation signal. A frequency of a secondsignal is detected (804). For example, the second signal may be theoutput of a signal generator such as, for example, a VCO or a VCXO. Adifference signal (e.g., control signal) is determined based on thecenter frequency of the input signal and the frequency of the secondsignal (806). For example, the difference signal represents a differencein frequency between the center frequency of the input signal and thefrequency of the second signal. In some examples, difference signal is aDC voltage signal.

The frequency of the second signal is modified based on the differencesignal to provide the carrier signal of the input signal (808), and thesecond signal is outputted as the carrier signal from the deviceperforming the process 800 (810). For example, a difference signal canbe a control signal for the signal generator and can cause the signalgenerator to adjust the frequency of its output signal. The frequency ofthe second signal modified until it is matched to the center frequencyof the input signal. In some examples, the frequency of the secondsignal is matched to the center frequency of the input signal when thedifference signal reaches a minimum value. In some examples, the minimumvalue may be a threshold value indicating that the difference betweenthe frequency of the second signal in the center frequency of inputsignal is within an allowable tolerance. In some examples, the minimumvalue may be a magnitude of the different signal voltage that is belowthe threshold minimum voltage magnitude.

FIG. 9 depicts an example process 900 for separating TM signals frominput signals that can be executed in accordance with implementations ofthe present disclosure. In some examples, the example process 900 can beprovided as computer-executable instructions executed using one or moreprocessing devices (e.g., a digital signal processor) or computingdevices. In some examples, the process 900 may be hardwired electricalcircuitry, for example, as an ASIC or an FPGA device. In some examples,the process 900 may be executed by an SDR.

An input signal including a carrier signal modulated with a firstmodulation signal and a second modulation signal is received 902). Forexample, the first modulation signal may be a traditional type ofmodulation signal such as, for example, FM, AM, PM, QAM, APSK, etc. Thesecond modulation signal may be a TM modulation signal. The firstmodulation signal is demodulated from the input signal (904). Forexample, the first modulation signal can be demodulated usingtraditional the modulation techniques. Because traditional demodulationtechniques do not recognize TM modulation, the resulting demodulatedfirst modulation signal will not include the TM modulation signal.

The carrier signal is re-modulated using the demodulated firstmodulation signal to generate a third signal (906). For example, thethird signal includes an un-modulated carrier signal modulated with thefirst modulation signal. The un-modulated carrier signal has the samefrequency as the carrier of the input signal. The first modulationsignal is removed from the input signal by subtracting the third signalfrom the input signal (908) to extract the second modulation signal(e.g., the TM modulation signal) from the input signal. In someexamples, the input signal must be delayed an appropriate amount of timeto ensure that it is in phase with the third signal. That is, due to thedemodulation and re-modulation process the third signal may be out ofphase with the original input signal. Thus, before subtracting the thirdsignal from the input signal, the input signal can be delayed anappropriate amount of time. The extracted second modulation signal isprovided to a signal demodulator (910). For example, an extracted TMmodulated signal can be provided to a TM signal demodulator fordemodulation.

While the present disclosure is generally directed to generatingtranspostional modulated signals and demodulating transpostionalmodulated signals using a third harmonic of a carrier signal, in someimplementations transpostional modulated signals can be generated anddemodulated by using other harmonics of a carrier signal (e.g., a fourthharmonic, fifth harmonic, sixth harmonic, etc.).

Implementations of the subject matter and the operations described inthis specification can be realized in analog or digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Implementationsof the subject matter described in this specification can be realizedusing one or more computer programs, i.e., one or more modules ofcomputer program instructions, encoded on computer storage medium forexecution by, or to control the operation of, data processing apparatus.Alternatively or in addition, the program instructions can be encoded onan artificially generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal; a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing. The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application-specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram can, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. Elements of a computer can include aprocessor for performing actions in accordance with instructions and oneor more memory devices for storing instructions and data. Moreover, acomputer can be embedded in another device, e.g., a mobile telephone, apersonal digital assistant (PDA), a mobile audio or video player, a gameconsole, a Global Positioning System (GPS) receiver, or a portablestorage device (e.g., a universal serial bus (USB) flash drive), to namejust a few. Devices suitable for storing computer program instructionsand data include all forms of non-volatile memory, media and memorydevices, including by way of example semiconductor memory devices, e.g.,EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internalhard disks or removable disks; magneto-optical disks; and CD-ROM andDVD-ROM disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyimplementation of the present disclosure or of what can be claimed, butrather as descriptions of features specific to example implementations.Certain features that are described in this specification in the contextof separate implementations can also be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation can also be implemented inmultiple implementations separately or in any suitable sub-combination.Moreover, although features can be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination can be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingcan be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results. Inaddition, the processes depicted in the accompanying figures do notnecessarily require the particular order shown, or sequential order, toachieve desirable results. In certain implementations, multitasking andparallel processing can be advantageous.

1. A device comprising: one or more processors; a receiver coupled tothe one or more processors; a transmitter coupled to the one or moreprocessors; and a data store coupled to the one or more processorshaving instructions stored thereon which, when executed by the one ormore processors, causes the one or more processors to perform operationscomprising: receiving a first signal from a second device, the firstsignal including a carrier signal modulated with a first modulationsignal; detecting a frequency of the carrier signal by performing acarrier extraction (CAREX) process on the first signal; adding a secondmodulation signal to the carrier signal of the first signal to produce acombined signal, wherein the second modulation signal is atranspositional modulation (TM) signal and the first modulation signalis a non-TM signal; and transmitting the combined signal.